/* ECMASCript默认数据类型有：
1.Undefined
2.Null
3.Boolean
4.Number
5.String
6.Object
7.Symbol */

let message = "hello world";
console.log(typeof message);
console.log(typeof 123);

let text = " sigma: \u03A3";
console.log(text);

console.log(text.length);

let num = 10;
console.log(num.toString(16));
